Microstructures, densification and mechanical properties of TiC-Al2O3-Al composite by field-activated combustion synthesis

Dense TiC-Al2O3-Al composite was prepared with Al, C and TiO2 powders by means of electric field-activated combustion synthesis and infiltration of the molten metal (here Al) into the synthesized TiC-Al2O3 ceramic. An external electric field can effectively improve the adiabatic combustion temperature of the reactive system and overcome the thermodynamic limitation of reaction with x < 10 mol. Thereby, it can induce a self-sustaining combustion synthesis process. During the formation of Al2O3-TiC-Al composite, Al is molten first, and reacted with TiO2 to form Al2O3, followed by the formation of TiC through the reaction between the displaced Ti and C. Highly dense TiC-Al2O3-Al with relative density of up to 92.5% was directly fabricated with the application of a 14 mol excess Al content and a 25 V cm-1 field strength, in which TiC and Al2O3 particles possess fine-structured sizes of 0.2-1.0 μm, with uniform distribution in metal Al. The hardness, bending strength and fracture toughness of the synthesized TiC-Al2O3-Al composite are 56.5 GPa, 531 MPa and 10.96 MPa m1/2, respectively